
package com.e885.hibernate;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;

import com.e885.log.E885Logger;

/**
 * Configures and provides access to Hibernate sessions, tied to the current thread of execution. Follows the Thread Local Session pattern,
 * see {@link http://hibernate.org/42.html }.
 */
public class HibernateSessionFactory
{

	/**
	 * Location of hibernate.cfg.xml file. Location should be on the classpath as Hibernate uses #resourceAsStream style lookup for its
	 * configuration file. The default classpath location of the hibernate config file is in the default package. Use #setConfigFile() to
	 * update the location of the configuration file for the current session.
	 */
	private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";

	private static final ThreadLocal threadLocal = new ThreadLocal();

	private static Configuration configuration = new Configuration();

	private static org.hibernate.SessionFactory sessionFactory;

	private static String configFile = CONFIG_FILE_LOCATION;

	static
	{
		try
		{
			configuration.configure( configFile );
			sessionFactory = configuration.buildSessionFactory();
		}
		catch( Exception e )
		{
			E885Logger.hibernateLog.error( "%%%% Error Creating SessionFactory %%%%" );
			e.printStackTrace();
		}
	}

	private HibernateSessionFactory()
	{
	}

	/**
	 * Returns the ThreadLocal Session instance. Lazy initialize the <code>SessionFactory</code> if needed.
	 * 
	 * @return Session
	 * @throws HibernateException
	 */
	public static Session getSession() throws HibernateException
	{
		Session session = ( Session )threadLocal.get();

		if( session == null || !session.isOpen() )
		{
			if( sessionFactory == null )
			{
				rebuildSessionFactory();
			}
			session = ( sessionFactory != null ) ? sessionFactory.openSession() : null;
			threadLocal.set( session );
		}

		E885Logger.hibernateLog.debug( "session:[" + session + "]" );

		return session;
	}

	/**
	 * Rebuild hibernate session factory
	 * 
	 */
	public static void rebuildSessionFactory()
	{
		try
		{
			configuration.configure( configFile );
			sessionFactory = configuration.buildSessionFactory();
		}
		catch( Exception e )
		{
			E885Logger.hibernateLog.error( "%%%% Error Creating SessionFactory %%%%" );
			e.printStackTrace();
		}
	}

	/**
	 * Close the single hibernate session instance.
	 * 
	 * @throws HibernateException
	 */
	public static void closeSession() throws HibernateException
	{
		Session session = ( Session )threadLocal.get();
		threadLocal.set( null );

		if( session != null )
		{
			session.close();
		}
	}

	/**
	 * return session factory
	 * 
	 */
	public static org.hibernate.SessionFactory getSessionFactory()
	{
		return sessionFactory;
	}

	/**
	 * return session factory
	 * 
	 * session factory will be rebuilded in the next call
	 */
	public static void setConfigFile( String configFile )
	{
		HibernateSessionFactory.configFile = configFile;
		sessionFactory = null;
	}

	/**
	 * return hibernate configuration
	 * 
	 */
	public static Configuration getConfiguration()
	{
		return configuration;
	}

}